Future energy efficient buildings will aim at being free from the use of fossil fuels. FIGS. 1, 1a show a building 1 having mixed use residential/commercial space 5. Clean energy is derived from the building's shape which functions as a solar collector as the earth orbits the sun. Wind energy is derived from a turbine section 4. See Pub. No. US2006/0156725 incorporated herein by reference. Curtain wall material-science technology panels are used throughout wherein the panels reflect solar heat in the summer and transmit solar heat in the winter. All black and grey water exits separate pipes in shaft 7. A black/grey waste processing system 6 includes mixing systems in digesters 8. Oxygen producing plants 3 are incorporated in the terraced roof system that can be a greenhouse. The waste processing system 6 could generate enough electricity to power building 1. The black and grey water shaft 7 enter a single stream recycle waste storage bin set 70. Next a grey waste clarifier 71 clarifies the grey waste. Nest the settled grey waste is held in bins 72. Next a sewage clarifier 73 further clarifies the settled grey waste from bins 72. Next the liquid pretreatment processor 73 readies the slurry for injection into the digesters 8. Output from the digesters 8 includes a water treatment facility 74, and biogas goes to the biogas treatment processor 75. Next the biogas goes to the natural gas pipeline 76 to the facility boilers 77. Steam from the facility boilers 77 powers the electric generators 78. The composter reactor 79 readies the solid waste for removal. A microfiltration unit 80 readies digester water output for delivery to the storage pond 81, which could also hold excess from clarifiers 71, 73.
The main aspect of the present invention is to improve the efficiency of the digesters 8, or in any vertical liquid slurry vessel.
Related art includes U.S. Pat. No. 4,690,764 (1987) to Okumura et al. which discloses a horizontal aerator using a pressurized liquid nozzle nested in a gas inlet nozzle assembly, wherein oxygen in small bubbles is mixed into the raw water liquid. A fluid straightener ejects the aerated mixture into a water tank.
U.S. Pat. No. 5,942,116 (1999) discloses an anaerobic sludge digester having an egg shape. A central draft tube has pump to pump settled sludge at the bottom of the vessel up the tube to the top where spray nozzles create motion on the top surface.
The present invention is an apparatus for mixing both homogeneous liquids and non-homogeneous liquid slurries in vessels/reactors of varying geometry. Non-homogeneous slurries include mixtures of liquids, solids and gases in varying relative concentrations. The solids in non-homogeneous liquid slurries include both floating and settling constituents. The apparatus is capable of fully entraining floating and sinking solids for the purpose of promoting a chemical or biological reaction that changes the relative constituency of the slurry components that can vary from inert solids of varying size to complex organic molecules and particles.
Reactor dynamics can include control of slurries that can segregate in a variety of ways. Slurries can include a fully homogeneous liquid mixture entraining non-homogeneous materials. This material includes light solids trapped by rising gas bubbles that form a froth on the surface of the slurry. Materials of both high and low specific gravity tending to float or sink unless acted on by a positive mixing velocity gradient and fibrous and stringy materials. In many cases the ability of a reactor to perform the intended chemical/biological function depends on the operation of a device that blends both floating and settled slurry components with the liquid and neutrally buoyant slurry mass.
Reaction vessels can be built in many configurations. However, tall cylinders present an economical configuration for most reactor vessels that include both low and high-pressure environments. A variety of systems have been developed to accomplish the complete mixing of these reactors. Mixer types include submerged impeller gas bubble and jet draft tube and liquid jet types. Mixing devices differ in the way they accomplish entrainment of the vessel contents in the three general zones of interest within the reactor. These zones from top to bottom are the surface where slurry components can accumulate as a scum or froth. the center which includes suspended slurry components and the bottom where high specific gravity materials settle when mixing gradients are insufficient to maintain the material in the center mix zone.
It can be shown that the energy required of a given mixing system to completely entrain all components of a mixed slurry is greatest for vessel bottoms and surfaces where a range of from low to high specific gravity solids are present. Mixers can be designed either to induce sufficient energy into the slurry in the form of localized slurry velocity to completely mix all zones of the reactor or selectively mix specific zones of the vessel with the intent to direct sufficient energy to accomplish acceptable component-entrapment. The former method uses the largest amount of energy to accomplish mixing, while the latter requires a more complex system to do the work.
A simple mixer design capable of mixing liquid slurry in all zones of a vessel/reactor is needed as an improved, more efficient, more effective and more reliable method to do the work.
The present invention uses a double channel central draft tube. A pump forces fluid through a downward facing nozzle in the central channel. The high velocity fluid induces a vacuum in the outer channel to draw in sludge at various levels of the draft tube. The combined flows from the central and outer channels exit a second nozzle to hit the bottom of the vessel.